Thousands of people around the world have been diagnosed with colon cancer, hundreds ultimately dying of the disease. Patients are typically treated with colon resection surgery, followed by radiation therapy or systemic chemotherapy, the therapy being based on macroscopic traits of the tumor and the tumor stage. The 5-year relapse-free survival rate is improved in some patients receiving chemotherapy after colon surgical resection surgery, while this statistic is not improved in others.
Diagnostic tests for predicting relapse in colon cancer include the Oncotype DX test (Genomic Health). However, Genomic Health's test and others reports of a test for relapse in colon cancer is widely considered a failure. The Oncotype DX Colon test identifies a small group of poor prognosis patients, but the test does not isolate good prognosis patients who can avoid further therapy, such as chemotherapy. Unfortunately, there does not exist a prognostic test for colon cancer that provides a consistent and accurate assessment of colon relapse risk in clinical practice.
Painful and expensive therapies, such as chemotherapy, are typically part of a standard and routinely proscribed clinical care management protocol for the post-colon cancer resection patient. Chemotherapy is routinely recommended for patients with stage III or IV tumors.1 While chemotherapy is of some benefit for stage II colon cancers1, 82% of these patients will survive for 5 years without further treatment.1 Only about 10% of the patients who do not receive chemotherapy reportedly die of the disease within 5 years. A method of predicting the patient population that can safely avoid chemotherapy apart from that population that will likely benefit from chemotherapy, will save lives, relieve thousands of people from the toxic side effects of unnecessary chemotherapy, and save significant healthcare expense worldwide. However, there is no reliable method in existence that is capable of accurately predicting which of these patient populations could successfully avoid the painful and toxic process of chemotherapy without risk of relapse.
There is growing evidence that right-side colon cancer (RCC) and left-side colon cancer (LCC) have significantly different histological and molecular characteristics. For example, RCC is more common in women than men, and patients with RCC have a poorer prognosis than patients with LCC3,4. RCC and LCC tend to have different gross macroscopic pathology5. At the molecular level, a significant number of genes are differentially expressed between RCC and LCC6, and patterns of loss of heterozygosity and promoter methylation vary by location7.
Despite these observations, the challenge of colon cancer treatment remains to target specific treatment regimens to pathogenically distinct tumor types, and ultimately personalize colon cancer treatment in order to maximize outcomes. Hence, a need exists for materials and tests that are simultaneously prognostic and provide predictive information about colon cancer patient responses to treatment options. A medical need continues to exist for improved colon cancer clinical screening tools to enable more effective and less toxic colon cancer care and treatment management, and that also closely correlates with a high confidence level of long-term, relapse-free survival probability after colon cancer resection surgery.